Demand control ventilation system with commissioning and checkout sequence control

ABSTRACT

The disclosure relates to a Demand Control Ventilation (DCV) and/or Economizer system that is capable of drawing outside air into an HVAC air stream. In some instances, the DCV and/or Economizer system may be configured to help perform one or more system checks to help verify that the system is functioning properly. In some instances, the DCV and/or Economizer system may provide some level of manual control over certain hardware (e.g. dampers) to help commission the system. The DCV and/or Economizer system may store one or more settings and or parameters used during the commissioning process (either in the factory or in the field), so that these settings and/or parameters may be later accessed to verify that the DCV and/or Economizer system was commissioned and commissioned properly.

This application is a continuation of co-pending U.S. patent applicationSer. No. 12/828,889, filed Jul. 1, 2010, and entitled “DEMAND CONTROLVENTILATION SYSTEM WITH COMMISSIONING AND CHECKOUT SEQUENCE CONTROL”,which is: (1) a Continuation-In-Part (CIP) of U.S. patent applicationSer. No. 12/764,431, filed Apr. 21, 2010, and entitled “DEMAND CONTROLVENTILATION SYSTEM WITH REMOTE MONITORING”; and (2) is aContinuation-In-Part (CIP) of U.S. patent application Ser. No.12/764,415, filed Apr. 21, 2010, and entitled “AUTOMATIC CALIBRATION OFA DEMAND CONTROL VENTILATION SYSTEM”, all of which are incorporatedherein by reference.

TECHNICAL FIELD

The disclosure relates generally to Heating, Ventilation, and AirConditioning (HVAC) systems for conditioning the air of an inside spaceof a building or other structure, and more particularly, to economizerand/or demand control ventilation systems.

BACKGROUND

Most modern buildings use some sort of an HVAC system to control theenvironment conditions inside of the building. Such HVAC systems can beconfigured to control a number of different environmental conditionsincluding, for example, temperature, humidity, air quality and/or otherenvironmental conditions, as desired. In many HVAC systems, air from thebuilding's inside space is drawn into return ducts and provided back tothe HVAC system, where the return air is conditioned and provided backto the inside space. To meet desired ventilation requirements, some HVACsystems include demand control ventilation systems (DCV). Such systemsoften include an exhaust port for exhausting at least some of the returnair to the outside environment, and/or an intake port for bringing freshair into the HVAC system. In some instances, a damper system is providedto control how much return air is exhausted and/or how much outside airis brought into the building. In many instances, the air supplied by theHVAC system to the inside space can be a mixture of fresh outside airand return air, depending on the conditions.

In some cases, the exhaust and/or intake port can be part of aneconomizer unit, which in some instances can help provide the demandcontrol ventilation function. That is, in addition to providing adesired level of ventilation to the building, such an economizer may,under certain conditions, act as a first stage of cooling to helpdecrease energy usage of the HVAC system. In one example, the economizermay draw in cooler outside air to provide essentially “free” coolingduring some cooling cycles. Certain dampers, sensors, fans and/or otherhardware are often used to provide this functionality.

In many cases, such economizer and/or DCV systems are not properly setupor calibrated during the commissioning process, or are nevercommissioned at all. In some cases, the commissioning process can be arelatively complicated and time consuming process for a typicalinstallation technician, and therefore, the commissioning process is notalways done or done correctly. It would be desirable, therefore, toprovide a economizer and/or DCV system that is easier to commissionand/or easier to verify that commissioning was properly performed.

SUMMARY

The disclosure relates generally to Heating, Ventilation, and AirConditioning (HVAC) systems for conditioning the air of an inside spaceof a building or other structure, and more particularly, to economizerand/or demand control ventilation systems that are capable of drawingoutside air into an HVAC air stream. In some instances, the DCV and/orEconomizer system may be configured to help perform one or more systemchecks to help verify that the system is functioning properly. In someinstances, the DCV and/or Economizer system may provide some level ofmanual control over certain hardware (e.g. dampers) to help commissionthe system. The DCV and/or Economizer system may store one or moresettings and or parameters used during the commissioning process (eitherin the factory or in the field), so that these settings and/orparameters may be later accessed to verify that the DCV and/orEconomizer system was commissioned and commissioned properly.

The above summary is not intended to describe each disclosed embodimentor every implementation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description should be read with reference to the drawings.The drawings, which are not necessarily to scale, depict selectedillustrative embodiments and are not intended to limit the scope of thedisclosure. The disclosure may be more completely understood inconsideration of the following description of various illustrativeembodiments in connection with the accompanying drawings, in which:

FIG. 1 is a schematic diagram showing an illustrative HVAC system of abuilding including an economizer/demand control ventilation (DCV)system;

FIG. 2 is block diagram of an illustrative demand control ventilation(DCV) and/or economizer controller;

FIGS. 3A and 3B are block diagrams of an illustrative HVAC systemutilizing DCV and/or economizing control;

FIG. 4 is a block diagram of an illustrative damper calibration method;and

FIGS. 5A-5D show a block diagram of another illustrative dampercalibration method.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit aspects of the invention tothe particular embodiments described. On the contrary, the intention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DESCRIPTION

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the invention. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

FIG. 1 is a schematic diagram showing an illustrative Heating,Ventilation, and Air Conditioning (HVAC) system 102 of a building 104.The HVAC system 102 may include a Demand Control Ventilation (DCV)and/or Economizer system 130. The building 104 may be a residential,commercial, or any other suitable building. The HVAC system 102 mayinclude an HVAC unit 106, which in some cases may include one or moreheating and/or cooling units. In some embodiments, the HVAC unit(s) 106may be positioned on a rooftop (as in some commercial buildings) whereasin other embodiments, the HVAC unit(s) may be located within thebuilding. In the illustrative embodiment shown, the HVAC system 102includes an DCV and/or Economizer 130 upstream of the HVAC unit 106. TheDCV and/or Economizer 130 may include an outside air intake 108 and/oran exhaust vent 110. A return air stream 112 is shown for drawing returnair from the inside space of the building 104 through one or more returnregisters 114. The illustrative HVAC system 102 includes a fan 119,which may be a multiple or infinite speed fan, which can be controlledto induce an air flow through the HVAC unit 106 and to the building 104as shown at 116 through one or more supply registers 118. In some cases,the DCV and/or Economizer 130 may includes its own fan.

As shown, the DCV and/or Economizer system 130 of the HVAC system 102may employ one or more dampers within the various ducts of the DCVand/or Economizer system 130 to control air flows. In some instances,these dampers may include an exhaust damper 120 to regulate the fractionof the return air stream 112 that is exhausted 121 from the building104, an intake damper 122 to regulate the flow of an incoming outsideair stream 123 into the building 104, and/or a return damper 124 toregulate the flow of the retained return air stream 125 to mix with theincoming outside air stream 123. In some cases, the dampers 120, 122,and/or 124 may be mechanically coupled together to open and close in acoordinated manner, but this is not required. For example, in someillustrative embodiments, dampers 120 and 122 may open and closetogether or in sequence, and damper 124 may open and close in anopposite manner to dampers 120 and 122. When so provided, when damper122 is opened to allow more of the outside air stream 123 into thebuilding 104, damper 120 may also open to allow a similar amount of thereturn air stream 112 to be exhausted 121 from the building 104. Thereturn air damper 124 may close as the dampers 120 and 122 open. Thisarrangement may help balance the pressure inside the HVAC system 102 andbuilding 104. In some illustrative embodiments, more or fewer of thedampers 120, 122, and 124 may be employed, but the teachings of thisdisclosure may be applied advantageously to any suitable HVAC system.

In some embodiments, the Demand control ventilation (DCV) system,including the dampers 120, 122, 124 and/or associated duct work, may beincluded in an economizer unit, but this is not required. Under someconditions, such an economizer unit may be used to provide a first stageof free cooling by mixing cooler incoming outside air 123 with thesometimes warmer retained return air 125 to provide a cooler mixed airstream 132 to the cooling coils of the HVAC unit 106. Note that in thepresent disclosure, “return air” may refer to the return air stream 112,before it has been (possibly) divided into an exhaust air stream 121 anda retained return air stream 125, and in other cases, “return air” or“return air stream” may refer to the retained return air stream,regardless of whether the retained return air stream includes the entirereturn air stream 112 or only a fraction thereof. It generally will beclear from context what “return air” refers to, and in the case ofreferring to the contribution of inside air to the mixed air stream 132,it generally is to be understood that the retained return air stream125, which originates from the return air stream 112, may be referred toas “return air.”

In some instances, the HVAC system 102 may include a heat exchangergenerally shown at 134 to transfer heat energy between the incomingoutside air stream 123 and the exhausted air stream 121, which may beuseful under some operating conditions.

Decisions for when and how to use the DCV and/or Economizer 130 maydepend on strategies that consider current and/or past conditions ofoutside air and/or indoor air. In some instances, the HVAC system 102 ofFIG. 1 may include one or more outdoor air sensors 136 for measuring oneor more parameters of the outside air. Current economizer strategies aretypically based on dry bulb temperature, enthalpy, a combination of thetwo, or a sensed enthalpy that approximates the two. These strategiesgenerally base a decision to economize (e.g., whether to draw in outsideair in amounts greater than those needed to meet Demand ControlVentilation requirements) on the outside air temperature or enthalpy andwhether there is a need to cool the inside space of the building 104.

The HVAC system of FIG. 1 may include one or more inside air sensors 138for measuring one or more parameters of the air of the inside space ofthe building 104. Alternatively, or in addition, one or more return airstream sensors 140 may be provided to measure parameters of the air ofthe inside space, given that the return air stream 112 is drawn from theinside space of the building 104. In some cases, a mixed air sensor 144may be provided. Any of inside 138, return 140, mixed 114, and outside136 sensors may be configured to determine one or more air parameters ofinterest, such as dry bulb temperature, wet bulb temperature, dew point(i.e., dew point temperature), relative humidity, and/or enthalpy (i.e.,specific enthalpy), to name a few. Notably, these air parameters are notall independent. With appropriate assumptions (e.g., ideal gases, etc.),their interrelationship may be expressed through psychrometric equationsand represented graphically, for example on a psychrometric chart, ornumerically as desired. Some desired air parameters may be obtained frommeasurements of two other appropriately chosen air parameters. Forexample, dew point and/or enthalpy may be calculated from measuredvalues of dry bulb temperature and relative humidity. In someillustrative embodiments, any of inside 138, return 140, mixed 114,and/or outside 136 sensors may be configured to measure or determine twoor more air parameters selected from a set of parameters such as drybulb temperature, dew point, relative humidity, and/or enthalpy.

A controller, such as controller 142, may be provided to control theHVAC system 102. Controller 142 may be any suitable controller.Controller 142 may be a controller for the entire HVAC system 102, orany appropriate subset or subsets of the HVAC system 102 such as the DCVand/or Economizer 130. Physically, it may be a stand-alone unit orunits, or it may be integrated with hardware, such as with DCV and/orEconomizer 130. Controller 142 may be configured to receive informationfrom any suitable source, such as the inside 138, return 140, mixed 144,and/or outside 136 sensors, and it may be configured to issue commandsto any appropriate component of the HVAC system 102, such as dampers120, 122, 124, fan 119, HVAC unit 106, etc. It is contemplated thatcontroller 142 may be configured and programmed in any suitable manner.

In the event that controller 142 is integrated with hardware or located,for instance with a rooftop unit, it may difficult to determine if theHVAC system 102 and/or DCV and/or Economizer 130 is functioning properlywithout physically visiting the controller 142. In some instances, aremote monitoring device, such as remote monitoring device 146, may beprovided to allow the building owner and/or building occupant to monitorthe HVAC system 102 and/or DCV/Economizer 130 without physicallyvisiting the controller 142 or the HVAC unit(s) 106. It is contemplatedthat in some embodiments, remote monitoring device 146 may be locatedwithin building 104, or other location which allows for convenientaccess to the remote monitoring device 146. In some instances, theremote monitoring device 146 may provide alerts and system faults inreal time to the user. In some embodiments, remote monitoring device 146may allow remote configuration of the HVAC system 102 and/orDCV/Economizer 130 in order to change control points or other parameterswithout physically visiting the system 102 as discussed in more detailwith respect to FIGS. 2, 3A and 3B. In some embodiments, the controller142 itself may be located within building 104, or other location whichallows for convenient access to the controller 142, but this is notrequired or even desired in all embodiments. This may, however, reducethe need for a separate remote monitoring device 146.

FIG. 2 is a block diagram of an illustrative DCV and/or Economizercontroller 210, which may be used in conjunction with the HVAC system ofFIG. 1. While controller 210 may be described as DCV and/or Economizercontroller 210, it should be understood the DCV control system and/oreconomizer system may function independently of one another and mayfunction on separate control loops, if both are present. Further, whilethe HVAC system 102 may be described as having an economizing functionand demand control ventilation capabilities, it should be understoodthat one may be present without the other. In the illustrativeembodiment, the controller 210 may include a control module 212, awireless interface 214, an optional user interface 216, and one or moresensors 218. However, this is just one example of a suitable controller.In some cases, the one or more sensors 218 may include a temperaturesensor, a humidity sensor, a ventilation sensor, an air quality sensor(e.g. CO2 sensors), and/or any other suitable HVAC building controlsystem sensor, as desired. Temperature sensor(s) may be provided tosense the indoor, outdoor temperatures and/or mixed air temperatures.Likewise, humidity sensor may be provided to sense the humidity of theindoor, outdoor and/or mixed air. As illustrated, the one or moresensors 218 may be included with the Controller 210, such as within ahousing of Controller 210. However, it is contemplated that one or moresensors 218 may be located remote from the Controller 210, but incommunication therewith, if desired.

Control module 212 of the illustrative Controller 210 may be configuredto help control the comfort level (i.e. heating, cooling, ventilation,and/or air quality, etc.) of at least a portion of the building orstructure 104 by controlling one or more dampers 120, 122, 124 and/oractivating one or more HVAC components 106, as illustrative in FIG. 1.In some instances, control module 212 may include a processor 220 and amemory 222. Control module 212 may be configured to control and/or setone or more HVAC functions, such as, for example, HVAC schedules,temperature setpoints, humidity setpoints, trend logs, timers, fanspeeds, damper positions, environment sensing, and/or other HVACfunctions or programs, as desired. In some cases, control module 212 maybe used to configure one or more settings of the HVAC controller, suchas, for example, HVAC controller schedules including ventilationschedules, temperature setpoints, humidity setpoints, trend logs,timers, fan speeds, damper positions, environment sensing, HVACcontroller programs, user preferences, and/or other HVAC controllersettings, as desired. In the illustrative embodiment, control module 212may help control the comfort level of at least a portion of the buildingor structure using the temperature sensed by temperature sensor of theone or more sensors 218, when provided.

A memory 222 may be used to store any desired information, such as theaforementioned HVAC schedules, temperature setpoints, humiditysetpoints, trend logs, timers, fan speeds, damper positions,environmental settings, and any other settings and/or information asdesired. Control module 12 may store information within memory 222 andmay subsequently retrieve the stored information. Memory 222 may includeany suitable type of memory, such as, for example, random-access memory(RAM), read-only member (ROM), electrically erasable programmableread-only memory (EEPROM), Flash memory, or any other suitable memory,as desired. In some instances, memory 222 may store one or more controlprograms for execution by the processor 220.

When present, wireless interface 214 of the Controller 210 may beconfigured to wirelessly communicate (i.e. transmit and/or receivesignals) with a wireless interface of one or more HVAC controllers(and/or HVAC components 106). For example, wireless interface 214 may beconfigured to communicate with a wireless interface of an HVACcontroller and send and/or receive signals corresponding to, forexample, a temperature sensed by temperature sensor, a humidity sensedby the humidity sensor, heat and/or cool set points, ventilationsettings, indoor and/or outdoor air temperatures, equipment status,scheduling, trend logs, and/or any other suitable information and/ordata. It is contemplated that the wireless interface 214 may include,for example, a radio frequency (RF) wireless interface, an infraredwireless interface, a microwave wireless interface, an opticalinterface, and/or any other suitable wireless interface, as desired.While a wireless interface 214 is shown in FIG. 2, it is contemplatedthat a wired interface may be used instead, or in addition to, thewireless interface 214.

The optional user interface 216 may be any suitable interface that isconfigured to display and/or solicit information as well as permit auser to enter data and/or other settings, as desired. In some cases,user interface 216 may allow a user or technician to program and/ormodify one or more control parameters of Controller 210, such asprogramming a set point, a time, an equipment status and/or parameter,as desired. In some instances, the user interface 216 may include atouch screen, a liquid crystal display (LCD) panel and keypad, a dotmatrix display, a computer, buttons, one or more LED's and/or any othersuitable interface, as desired. In one example, at least some of theparameters and/or settings may be transmitted to the Controller 210 viawireless interface 214, but this is not required or even desired in allembodiments. In some instances, user interface 216 may be configured toalert the user to system faults occurring in the system using, forexample, audio and/or visual alerts. In some cases, Controller 210 mayonly control the DCV and/or Economizer system, and not the HVAC systemmore generally.

In some embodiments, the HVAC system 102, such as illustrated in FIG. 1,may include a Controller 210 that is programmed to control ventilationto the building 104 based on actual occupancy using carbon dioxide (CO2)sensors. Alternatively, or in addition, Controller 210 may be programmedto control ventilation to the building 104 based on a ventilationschedule, or a combination of actual occupancy and a ventilationschedule. In either case, it contemplated that controller 210 may allowthe ventilation rate to vary based on actual or scheduled occupancy,rather than requiring a maximum ventilation rate at all occupied times.Because buildings are rarely, if ever, at maximum occupancy at alltimes, Controller 210 may, if desired, provide substantial energy and/orcost savings by not requiring the ventilation rate to be at the maximumventilation rate during all occupied time periods.

FIGS. 3A and 3B are block diagrams 300 illustrating how an illustrativeDCV and/or economizer controller 302 may interact with the variouscomponents of the HVAC system 102. This is, however, just one example.In the example shown, a programmable controller, such as a thermostat306, may be provided to control the HVAC unit(s) 106. The thermostat 306may be in communication with the HVAC unit(s) 106, which in someinstances may be rooftop unit(s) 304, however it is contemplated theHVAC unit(s) 106 may be located within the building or at some otherlocation. The thermostat 306 may be configured to be programmable suchthat the building may be heated and/or cooled according to a desiredschedule. In some instances, the thermostat 306 may communicate with therooftop (or other) unit(s) 304 to turn the unit(s) 304 on and off asneeded. In some embodiments, the thermostat 306 may be hardwired to therooftop (or other) unit(s) 304 while in other embodiments, thethermostat 306 may be in wireless communication with the rooftop unit(s)304.

The thermostat 306 may be part of or in communication with a DCV and/oreconomizer controller 302. As discussed above, DCV and/or economizercontroller 302 may be programmed to control ventilation to the building104 based, for example, on actual occupancy using carbon dioxide (CO₂)sensors. For example, in addition to operating the HVAC unit(s) toprovide a desired temperature, the HVAC system 102 may also beconfigured to bring a certain amount of fresh ventilation into abuilding as set out in, for example, building codes. When DCV and/orEconomizer controller 302 is so provided, DCV and/or Economizercontroller 302 may communicate with damper actuator 308 to selectivelyopen and close dampers based on the amount of ventilation needed. Forexample DCV and/or Economizer controller 302 may receive a signal from aCO₂ sensor 312. When the amount of CO₂ in the building reaches athreshold level, the DCV and/or Economizer controller 302 may relay asignal to the damper actuator 308 to open a damper (for example, damper122 in FIG. 1) to provide more fresh air to the building. Likewise, whenthe amount of CO₂ in the building falls below a threshold level, the DCVand/or economizer controller 302 may relay a signal to the damperactuator 308 to close or partially close a damper (for example, damper122 in FIG. 1) to minimize the amount of conditioned air that is lost toatmosphere. In some instances, the damper actuator 308 may include adirect coupled actuator (DCA) such that the controller 302 maycommunicate digitally with the actuator 308. DCV and/or economizercontroller 302 may also receive signals from other sensors such mixedair temperature 310, outdoor air temperature and/or humidity 314, andreturn air temperature and/or humidity 316 sensors. These parameters maybe used to determine, for example, whether or not the DCV and/orEconomizer controller 302 will draw in outside air in amounts greaterthan those needed to meet Demand Control Ventilation requirements.

In some instances, the DCV and/or Economizer controller 302 may be incommunication with a remote monitoring device 318, or may beincorporated into the remote monitoring device 318, but this is notrequired or even desired in all embodiments. In one illustrativeexample, remote monitoring device 318 may display operational parameterswhich may allow the user to monitor the HVAC system 102 remotely. Forexample, the remote monitoring device 318 may indicate that status of anHVAC unit (e.g. on/off), if free cooling (economizer mode) is available,DCV status (e.g. on/off), temperature/humidity readings from the varioussensors, CO₂ levels (parts per million, ppm), fan speed (e.g. low/high),building occupancy, etc. The remote monitoring device 318 may be furtherconfigured to allow a user to input various parameters such as CO₂threshold setpoints, temperature setpoints, percent of ventilation athigh/low fan speeds, minimum and maximum calibration ventilation flowrates at one or more calibration damper positions—sometimes at variousfan speeds, etc., to be provided to the DCV and/or economizer controller302. The remote monitoring device 318 may be further configured toprovide a user with system alerts and/or system faults. For example, theremote monitoring device may be able to alert the user to a malfunctionwithin the rooftop unit 304 that the user may otherwise be unaware ofThis may allow a user to maintain a DCV system/economizer 130 moreeffectively. The remote monitoring device 318 may be configured toprovide an alert such as, but not limited to, an audible alarm, anindicator light, and/or display and/or send a message when a fault hasbeen detected. The remote monitoring device 318 may be in communicationwith the controller 302 via a wired, wireless or any other suitableinterface, as desired. It is contemplated that in some instances the DCVand/or economizer controller 302 may be capable of displayingoperational parameters, receiving user inputs, and/or providing alerts.

As illustrated in FIG. 3B, in some instances, the remote monitoringdevice may be in communication with a computer 320, or other datalogging system. Such a data logging system may allow a user to monitorthe trends of the system 102, which might help a user more effectivelyprogram and/or operate the HVAC system 102. For example, the user may beable to retrieve historical system data such as when the system 102 wasable to function in economize and/or demand control modes. This may helpthe user and/or the controller 302 to better predict necessary systemmaintenance or when calibration of the system might be warranted.

In one illustrative embodiment, and prior to operating controller 302,the system 102 may be calibrated based on a minimum and a maximumdesired ventilation rate by, for example, changing the damper positionsand/or changing a fan speed (e.g. of fan 119) between a low and a highsetting. In some instances, the HVAC system 102 may be automaticallycalibrated from time to time, or in some cases, effectively continuouslycalibrated. As used herein, calibration may refer to, among otherthings, calibration of the system during initial installation of thesystem, or a re-calibration of the system during a subsequent systemcheckout (e.g. to help ensure proper functioning after the initialcalibration). In some cases, the controller 302 may be calibrated atboth a maximum fan speed and a minimum fan speed, for both a codemandated ventilation rate required for the building 104 during maximumoccupancy (hereinafter Vbz) and for a code mandated minimum ventilationrate required for building material out-gassing (hereinafter Va).

The calibration/commissioning process may include calibrating minimum(Va) and maximum (Vbz) damper position settings based on desired minimumand maximum ventilation rates. These damper settings are sometimescalled out in the HVAC system design documents for the building suppliedby an engineering firm that designed the system, and may be expressed asa percentage of ventilation (or percentage of fresh air in the mixed airstream). To help program the system's 102 minimum and maximumventilation rates, temporary or permanent calibration sensors may beplaced at the outside air intake 108, the return air duct 112 and/or atthe mixed air duct 132. In one example, temperature may be used tomeasure ventilation rate. In some cases, a minimum differential of 10degrees Fahrenheit is desired between the return air temperature (RAT)and the outdoor air temperature (OAT) to conduct a calibration. Oncethis condition is met, the following readings may be collected, and thereadings may be used as inputs to Equation 1 below:

(OAT−RAT)×% Ventilation+RAT=MAT  {Equation 1}

-   where OAT=Outside air temperature, RAT=Return air temperature, and    MAT=Mixed air temperature. During the calibration, the outdoor    and/or return air dampers may be repositioned by the controller    until the correct ventilation percentage (% Ventilation) is achieved    for each minimum and maximum ventilation settings. The controller    302 may then be programmed to interpolate an intermediate    ventilation rate, depending on actual, sensed or scheduled    occupancy, by modulating between these two calibrated damper    positions (or extrapolating beyond the values). This calibration may    be performed for each fan speed of fan 119 of the HVAC system 102.

In some cases, the controller 302 may be programmed to use a mixed airtemperature sensor to determine a return air temperature and/or anoutside air temperature. In one example, and to determine the fresh airtemperature, the controller 302 may close return air damper 124 and openfresh air damper 122 (see FIG. 1). Under these conditions, the mixed airstream will be mostly fresh outside air, and thus once stabilized, themixed air temperature sensor 144 will sense the temperature of the freshoutside air. Likewise, to determine the return air temperature, thecontroller 302 may close fresh air damper 122 and open return air damper124 (see FIG. 1). Under these conditions, the mixed air stream will bemostly return air, and thus once stabilized, the mixed air temperaturesensor 144 will sense the temperature of the return air. This proceduremay be used by the controller 302 to help determine the return airtemperature and/or the outside air temperature when no return airtemperature sensor and/or outside air temperature sensor are provided,or have failed.

In some instances, it may be desirable for a technician commissioningthe system 130, an original equipment manufacturer (OEM), and/or aninstaller to test the DVC and/or Economizer 130 upon installation,system start-up, or on-demand, as desired. In some illustrativeembodiments, the DCV and/or Economizer system 130 may be configured toperform system checks to help verify that the system was commissionedcorrectly and is/was functioning properly. In some cases, the DCV and/orEconomizer system may include a controller that provides support forsome level of self-testing including, for example, proving that one ormore dampers move to certain open and closed positions under certainconditions, proving that one or more sensors are functioning properly,proving that one or more fans (if present) can be energized properly,and/or perform any other suitable self-test function, and provideconfirmation to the user. In some instances, the settings used duringthe commissioning process of the DCV and/or Economizer system 130(either in the factory or in the field) may be stored in a memory, suchas memory 222 of the controller, where they can be later downloaded toverify that the particular DCV and/or Economizer system 130 was set upcorrectly. In some instances, it may be desirable to be able to verifydamper moves

In some embodiments, the a controller 302 may be configured such that auser can test one or more of the DCV and/or Economizer 130 functions(e.g. damper moves, mechanical cooling, etc) through a user interface(e.g. a user interface 216), through one or more physical terminal(s),through a wireless interface (e.g. a wireless interface 214), or throughany other suitable interface, as desired. In one example, the user maybe able to link a portable device such as, but not limited to, a laptopcomputer, a personal digital assistant (PDA), or a cellular phone (smartphone), directly to the controller 302 to initiate one or more systemtests. In some embodiments, the controller 302 may provide audio and/orvisual feedback (e.g. beeps and/or LEDs) to the user to help verify thatthe system 130 was commissioned properly and/or is functioning properly.Additionally, or alternatively, the controller 302 may provide audioand/or visual feedback to indicate the system is not functioningproperly or that an error has occurred. In some instances, thecontroller 302 may provide additional feedback, such as the set damperpositions, and/or other system control parameters. In some instances,the controller 302 may be configured to perform a system self-test uponsystem start-up. Alternatively, or in addition, the controller 302 maybe configured to perform a system self-test on demand, or at a user'sprompting. A result of the self-tests may be output to a user via a userinterface and/or stored in a memory for later viewing.

In some instances, the controller 302 may includes a test mode, whereinin the test mode, a user can independently control various aspects ofthe CV and/or Economizer 130 system, such as damper position, mechanicalcooling mode, fan operation, etc.

In some instances, the controller 302 may be configured to providefeedback, including such things as setup operating parameters providedduring a commissioning process, through a communication link to aportable device such as, but not limited to a personal digital assistant(PDA), a cellular phone (smart phone), or a laptop computer. In otherinstances, the controller 302 may be configured to wirelesslycommunicate with a remote monitoring device and/or thermostat. In yetother instances, the controller 302 may communicate such parameters witha local user interface that is local to the DCV and/or Economizer 130system (e.g. on the roof top).

The controller 302 may be further configured to store data and settingscompiled during the commissioning of the stem, for verification ofproper commissioning of the system. For example, in some instances, thecontroller 302 may be configured to store current set and reset damperpositions, a maximum and/or minimum damper position, air flowparameters, the date of commissioning, a person or company name thatperformed the commissioning, and/or other DCV and/or economizerparameters. This information may be accessed at a later date by, forexample, a building owner or utility representative to verify the DCVand/or economizer system 130 was properly commissioned and is/wasfunctioning. It is contemplated that this information may be transferredto a device used to initiate the system test and/or commissioning. Insome instances, the OEM (Original Equipment Manufacturer) may performsome system checks and/or commissioning of the economizer 130 (or otherequipment) before shipment, to help ensure that the equipment will meetthe desired specifications. The OEMs may store these system checksand/or commissioning parameters in a memory, such as a non-volatilememory in a controller 302, which may help certify that the economizer130 was in fact commissioned and/or functioning properly prior toshipment. The OEM may be able to retrieve the data from the controller302 and maintain the information within their own records for lateraccess. In some instances, the DCV and/or economizer 130 may be added orretrofitted to an existing rooftop unit (or other system). When soprovided, the commissioning data obtained during the installation of theDCV and/or economizer system 130 may be recorded by the installer in amemory such that the data can be subsequently recalled to help verifythat the system 130 was correctly commissioned and installed.

In some instances, it may be desirable for the controller 302 toautomatically calibrate the DCV and/or economizer system 130, but thisis not required. FIG. 4 is a flowchart of an illustrative method 400 forautomatically calibrating a DCV and/or economizer system 130. A user mayinput parameters into controller 302 relating to the ventilationrequirements 402 of the particular system 102/building 104. The user mayenter the parameters via a user interface (UI), sometimes directlycoupled to the controller 302, or into a remote user interface, such asremote monitoring device 318. For example, the user may enter themaximum ventilation rate the system is capable of providing (e.g. incubic feet per minute, CFM), the code mandated ventilation rate requiredfor the building 104 during maximum occupancy, Vbz, and the codemandated minimum ventilation rate required for building materialout-gassing, Va. In some cases, default values are provided for each ofthese parameters.

Based on the parameters, the controller 302 may calculate theventilation percentages 404 for Vbz and Va. The controller 302 may thenmonitor the signals from outdoor temperature sensor 314 and return airtemperature sensor 316 for suitable conditions for calibration, as shownat block 406. For example, the controller 302 may monitor thetemperature difference between the outdoor air and the return air for adifferential of at least 10 degrees Fahrenheit. Once such a condition isdetected, and in some cases, the controller 302 may compare the currentconditions to the conditions during the previous calibration 408. If thecurrent conditions are better than the conditions during the previouscalibration (e.g. a larger temperature differential), the controller 302may automatically recalibrate 412 the system 130 based on the currentconditions. If the current conditions are worse than the conditionsduring the previous calibration (e.g. a smaller temperaturedifferential), the controller 302 may do nothing 410 and continuemonitoring the temperature sensors 314, 316 for more ideal conditionsfor calibration at block 406.

In some embodiments, the controller 302 may automatically calibrate theDCV and/or economizer system 130 from time to time. When so provided,the DCV and/or economizer system 130 may continually optimize itself forchanging environmental and/or equipment conditions. In some instances,the controller 302 may be caused, either during system boot-up or in atest or calibration mode, to perform a complete system checkout in orderto help ensure that the HVAC system 102 is functioning properly.

FIGS. 5A-5D, in combination, show a flowchart of another illustrativemethod for calibrating the damper positions. In some cases, the damperpositions may be calibrated during the initial installation of the HVACsystem 102, and/or automatically from time to time during normal systemoperation. Referring to FIG. 5A, the damper calibration process 500 maybegin 502 during, for example, an initial system set-up, during anautomatic calibration process, and/or at user prompting (e.g. the useractivates a calibration mode in the controller 302). In someembodiments, the DCV and/or economizer controller 302 may continuallymonitor the environmental conditions, and when the environmentalconditions are suitable for a recalibration, the controller 302 may runa calibration algorithm.

Referring to block 504, the controller 302 may first determine if theDCV and/or economizer system 130 requires calibration 504. If not, thecontroller 302 does nothing and the damper calibration process is endedat block 542. If it is determined that the DCV and/or economizer system130 requires calibration, and in some illustrative embodiments, thecontroller 302 may disable all compressor stages 506 for the duration ofthe calibration process. The controller 302 may then check the returnair temperature sensor 508 for a valid return air temperature reading.Next, controller 302 may determine the temperature differential 314between the return air temperature and the outdoor air temperature. Inorder for the illustrative damper calibration process 500 to continue516, the temperature differential must meet the requirements (e.g.greater than 10° F.), and the current conditions must be better than theconditions under which the previous calibration occurred. If either ofthese is not true, the controller 302 does nothing and the dampercalibration process is ended at block 542.

If the current conditions meet the requirements 516, the controller 302may check for an optional expansion module 518. In some instances, anoptional expansion module 518 may provide extended input/outputcapabilities to the controller. For example, an expansion module 518 mayallow for multiple fan speeds (for example, but not limited to, high andlow fan speeds). If an expansion module 518 is present, the controller302 may then check the fan speed 520 of the HVAC system 102. If the fanspeed is set to low, the controller 302 may compute the percent ofventilation necessary 524 for both Va and Vbz at low fan speed (VaLS andVbzLS, respectively). The percent of ventilation at low fan speed may becalculated by the following equations:

VaLS=Va_CFM/MAX_CFM_LS  {Equation 2 }

VbzLS=Vbz_CFM/MAX_CFM_LS  {Equation 3}

-   where VaLS is the percent of ventilation for minimum building    occupancy at low fan speed, Va_CFM is the volume (in cubic feet per    minute) of air flow needed to meet the minimum ventilation    requirements, VbzLS is the percent of ventilation for maximum    building occupancy at low fan speed, Va_CFM is the volume (in cubic    feet per minute) of air flow needed to meet the maximum ventilation    requirements, and MAX_CFM_LS is the maximum amount of air volume (in    cubic feet per minute) the fan can provide at low fan speed.

If the fan speed is not low, or an expansion module 518 is notconnected, the controller 302 may compute the percent of ventilationnecessary 522 for both Va and Vbz at high fan speed (VaHS and VbzHS,respectively). The percent of ventilation at high fan speed may becalculated by the following equations:

VaHS=Va_CFM/MAX_CFM_HS  {Equation 4}

VbzHS=Vbz_CFM/MAX_CFM_HS  {Equation 5}

-   where VaHS is the percent of ventilation for minimum building    occupancy at high fan speed, Va_CFM is the volume (in cubic feet per    minute) of air flow needed to meet the minimum ventilation    requirements, VbzHS is the percent of ventilation for maximum    building occupancy at high fan speed, Va_CFM is the volume (in cubic    feet per minute) of air flow needed to meet the maximum ventilation    requirements, and MAX_CFM_HS is the maximum amount of air volume (in    cubic feet per minute) the fan can provide at high fan speed.

Once the percent of ventilation for Va and Vbz has been determined, thecontroller 302 may check if the minimum damper positions have beendetermined at block 526 to achieve the desired mixed air temperature(MAT) for Va. If the damper positions have not been determined, thecontroller 302 may compute 532 the mixed air temperature for Va giventhe sensed return air temperature, outside air temperature and thedesired percent of ventilation Va. The controller 302 may then adjustthe intake and/or exhaust dampers 122, 120 until the required MAT hasbeen reached, as indicated at block 534. The corresponding damperposition may be saved within a memory of the controller 302.

Once the damper position has been determined for Va, the controller 302may determine if a validation recheck 528 of the return air temperatureand temperature differential (RAT-OAT) has been performed. In someinstances, the damper calibration process 500 may be iterative such thatthe calibration process 500 is cycled through until the damper positionhas been determined for both Va and Vbz at a high fan speed and a lowfan speed (if available). In some instances, the damper positions for Vamay already be determined when the controller 302 arrives at thedecision block 526 for Va damper position. In this instance, thecontroller may not determine the damper position, but instead may checkif a validation recheck 528 of the return air temperature andtemperature differential (RAT-OAT) has been performed in order to helpensure that the calibration has been completed under suitableconditions. If a recheck 528 has not been performed, the dampers 120,122 may be closed and the conditions may be verified by beginning thetemperature sensor checks 508 again. In some embodiments, thecalibration of the damper positions 532, 534, 436, 538 may be performedwith an Adaptive Intelligent Action (AIA) function block.

If the recheck 528 has been performed, the controller 302 may compute536 the mixed air temperature for Vbz. The intake damper 122 may beopened at shown at block 538 until the required MAT has been reached.The corresponding damper positioned may be saved within a memory of thecontroller 302. Once the damper position has been determined for Vbz,the controller 302 may return control of the dampers for normal systemoperation 540, at which point the calibration process 500 is complete asshown at block 542. As discussed above, the calibration process 500 maybe performed at, for example, system boot up, at a predeterminedfrequency, upon user initiation through a test and calibration mode, andor at any other suitable time as desired.

Those skilled in the art will recognize that the present invention maybe manifested in a variety of forms other than the specific embodimentsdescribed and contemplated herein. Accordingly, departure in form anddetail may be made without departing from the scope and spirit of thepresent invention as described in the appended claims.

What is claimed is:
 1. A Demand Control Ventilation (DCV) and/orEconomizer system that is configured to be attached to a roof top HVACunit of a building, comprising: a DCV and/or economizer unit having adamper and a controller, wherein the damper is configured to selectivelycontrol air flow from outside of the building and into the building; thecontroller is configured to control a position of the damper such that adesired air flow of outside air is drawn into the building; and thecontroller is further configured to initiate and perform one or moretests of the DCV and/or economizer unit upon receiving one or more testcommands that are initiated by a user, the one or more tests comprisingproving that the damper can be successfully moved from a first positionto a second position, the controller is further configured tocommunicate a result of the one or more tests to a user interface. 2.The Demand Control Ventilation (DCV) and/or Economizer system of claim1, wherein the user interface is configured to: allow the user toinitiate the one or more test commands; and provide the result of theone or more tests to the user.
 3. The Demand Control Ventilation (DCV)and/or Economizer system of claim 2, wherein the user interface includesa display.
 4. The Demand Control Ventilation (DCV) and/or Economizersystem of claim 3, wherein the user interface is secured to the DCVand/or economizer unit and operatively coupled to the controller via awired connection.
 5. The Demand Control Ventilation (DCV) and/orEconomizer system of claim 3, wherein the user interface is part of aportable device, which is operatively coupled to the controller via awireless and/or wired connection.
 6. The Demand Control Ventilation(DCV) and/or Economizer system of claim 2, wherein the user interfaceincludes a button and provides audio and/or visual feedback.
 7. TheDemand Control Ventilation (DCV) and/or Economizer system of claim 1,wherein the DCV and/or economizer unit includes a sensor, and the one ormore tests comprises proving that the sensor is functioning.
 8. TheDemand Control Ventilation (DCV) and/or Economizer system of claim 1,wherein the DCV and/or economizer unit includes a fan and the one ormore tests comprises proving that the fan is functioning.
 9. The DemandControl Ventilation (DCV) and/or Economizer system of claim 1, whereinthe controller includes a non-volatile memory, and wherein thecontroller is configured to store the result of the one or more tests tothe non-volatile memory.
 10. A Demand Control Ventilation (DCV) and/orEconomizer system for a building, comprising: a DCV and/or economizerunit having a damper and a controller located at the DCV and/oreconomizer unit, the controller having a non-volatile memory, the damperhaving an open position and a closed position for controlling a flow ofoutside air into the building; the controller, in an operational mode,is configured to control the damper position such that a desired flow ofoutside air is drawn from outside the building and into the buildingwithout having to enter a test mode; and the controller, in the testmode, is configured to initiate and perform one or more self-tests ofthe DCV and/or economizer unit and to store a result of the one or moreself-tests in the non-volatile memory for later access by a user. 11.The Demand Control Ventilation (DCV) and/or Economizer system of claim10, wherein the controller is configured to enter the test mode andperform one or more of the self-tests after the controller is initiallybooted but before the controller enters the operational mode andcontrols the damper position such that a desired flow of outside air isdrawn from outside the building and into the building.
 12. The DemandControl Ventilation (DCV) and/or Economizer system of claim 10, whereinthe controller is configured to enter the test mode and perform one ormore of the self-tests on demand by a user.
 13. The Demand ControlVentilation (DCV) and/or Economizer system of claim 10, wherein theresult of the one or more self-tests is retrievable from thenon-volatile memory and displayed on a user interface.
 14. The DemandControl Ventilation (DCV) and/or Economizer system of claim 13, whereinthe user interface includes a display.
 15. The Demand ControlVentilation (DCV) and/or Economizer system of claim 13, wherein the userinterface is secured to the DCV and/or economizer unit and operativelycoupled to the controller via a wired connection.
 16. The Demand ControlVentilation (DCV) and/or Economizer system of claim 13, wherein the userinterface is part of a portable device, which can be operatively coupledto the controller via a wireless connection.
 17. The Demand ControlVentilation (DCV) and/or Economizer system of claim 13, wherein the userinterface includes a button and also provides audio and/or visualfeedback.
 18. The Demand Control Ventilation (DCV) and/or Economizersystem of claim 10, wherein the controller is configured toautomatically initiate and perform one or more of the self-tests. 19.The Demand Control Ventilation (DCV) and/or Economizer system of claim10, wherein one or more of the self-tests are configured to prove thatthe damper moves to predetermined open and/or closed positions, provethat one or more sensors of the DCV and/or economizer unit arefunctioning properly, and/or prove that one or more fans of the DCVand/or economizer unit can be energized properly.
 20. A Demand ControlVentilation (DCV) and/or Economizer system for a building, comprising: aDCV and/or economizer unit having a damper and a controller located atthe DCV and/or economizer unit, the controller having a non-volatilememory, the damper having a range of damper positions for controlling aflow of outside air into the building; the controller is configured tocontrol the damper position such that a desired flow of outside air isdrawn from outside of the building and into the building; and thecontroller is further configured to store system commission datagenerated during a commissioning of the DCV and/or economizer unit inthe non-volatile memory for later confirmation of the the commissioningof the DCV and/or economizer unit, the system commissioning datacomprising one or more of a current set and/or reset damper position, amaximum and/or minimum damper position, one or more air flow parameters,a date of commissioning, and a person and/or company name that performedthe commissioning.